Fluid motor



E'. G. GARTIN.

FLUID MOTOR.

ORIGINAL FILED JAN.14.1916'.-

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Patented dan.

narrar G. GARTIN, F CLAREMONT, NEIN HAMPSHIRE, ASSIGNOR T0 SULLIVAN llIACI-.INERY COMPANY, OF CLAREIIGNT, NEW HAMPSHIRE, A CORPORATION 0F MASSACHUSETTS.

FLUID MOTOR.

Application filed January 14,1916, Serial No. 72,165. `Renewed September 19, 1922. Serial No. 589,234.

To @ZZ whom it may concern.'

Be it known that I, Emma G. Gaiarin, a citizen of the United States,and a resident of Claremont, county of Sullivamftate of New Hampshire (Whose post-ofice address is Claremont, New Hampshire), have invented an Improvement in Fluid Motors, of which the following descriptiomin connection with the accompanying drawings, is a specification, like characters onthe draivings representing like parts. n

This invention pertains to improvements in direct acting fluid motors for use in rock drills or other percussive tools and particularly though not exclusively,V to valveless percussive fluid motors for use in hammer drills and the like.

A preferred construction of one embodiment of my invention is shown in the drawings and herein described forillustrative purpose, While the scope of my invention is more particularly pointed out in the appended claims.

In the drawings:

Figures l4 and 2 are partial longitudinal sections on the lines lf-l-l `of Fig. 3 of a preferred construction of the iiuid motor ef a hammer drill illustrative of one embodiment of my invention;

Figures 3 and 4 are sections thereof on the lines 3 3 and e-l respectively of nig. l.

Referring to the drawings I prefer to provide a motor cylinder 6 having a large piston chamber 'i' and a small piston chamber 8 in which may reciprocate a piston having an enlarged head 9 and a smaller head l0. I preferably use the fluid motor herein described in connection with a drill steel ll, drill steel rotating'means l2, pressure fluid feeding means and coordinated controlling mechanism, all substantially as invented by one George II. Gilman.

fressure fluid is supplied to the fluid motor from any suitable source through a supply conduit 13 preferably opening into the smaller piston chamber 8 through a preferably elongated port 14 Which is preferably so located as to connect at one extremity of the piston stroke With a grooved portion l5 of the piston and adapted to admit pressure fluid to the intermediate pressure receiving chamber 16, the pressure fluid acting on the area 16 of the piston head 9 and 55 tending to move the piston to the right.

(See Figs. l and 2.) I preferably provide a by-pass port 17 to conduct pressure fluid to the small piston chamber 8 preferably at the rear endthereof as shown to act on the pressure receiving area. 18 to assist in impelling the piston forward on its forward stroke. I prefer to return the piston by live air preferably acting expansively `on the return pressure receiving area 19 and to this end I may provide a return passage 20 connecting with the rear piston chamber 8 andWith the enlarged piston chamber 7. I preferably provide pressure fluid inlet means adapted to admit pressureiiuid to the Y.rear of the piston l0 Whenapproaching the forward limit of its stroke, so that live pressure fluid can be supplied to the return pressure receiving area through the return port 20. This pressure fluid inlet means may, if desired, be combined with the inletlif by f an elongation thereof and I have so shown it.

herein. I may supply a single exhaust portv 2l. to exhaust. fluid from both pressure rey-` ceiving areas of the piston `head 9.

When my invention is use-cL in connection with ahammer drill I prefer to interpose a. striking plug 22 of a Well-known type between the percussive piston andthe drillsteel ll. As shown in Figures 3 `and 4L, I prefer touse plural by-pass portsli' ,return ports 20, and exhaust ports 2l.

The embodiment of my invention illustrated,` operates as follows: Assuming the piston to be in the position shoivnin Ifg. l, pressure fluid admitted through the supply port ltpasses around the reduced porA tion l5 of the piston into the intermediate pressure chamber I6, and acts on the piston, upon the area 16 thereof, to impe-lj the piston forward. Pressure fluid also passes through the port 23 into the by-pass port 17' and thence into the smaller piston chamber 8 to act upon the pressure'arealiS to assist in driving the piston forward. After the piston has advanced a portion of kits stroke, the supply .port 14 is closed by the piston head l0 and the piston completes its Working` strokeby the expansive action of the pressure fluid. 1When lthe piston has nearly completed its forwardy stroke live pressure fluid isv admitted to the front of the piston to act on the pressure area 19 to return the piston. I prefer-to admit such fluid into the rear piston chamber 8 preferably through the port 14. andto conduct it loo llO

to the piston chamber 7 through the return port 20, all as shown in Fig. 2. The object of conducting the fluid supply for chamber 7 through the rear piston chamber 8 is to secure a delayed action of this pressure inA for chamber 7 into the chamber S, wherein the pu'essure has been much rcdu :ed ly ein pansion, to accomplish the required deiay in fluid transmission to chamber 7 after ports 1.4i and 2O are opened by the piston. After the return stroke has been started the 10 and the return stroke is completed by the expansive force of the pressure fluid in the piston chamber l, until the position shown in Fig. 1 is attained, after which the whole operation is repeated as described.. At or about the time the port 14 is closed, the port 23 is opened so that the air which would other "ise be highly compressed in the smaller piston chamber 8 is permitted to low through the passage 17 and around the recessed piston portion 15 to the intermediate chamber 16,so that the cushioning,- action of the compressed air is more evenly divided between the piston heads 18 and 9.

The very important feature of expansion into chamber 8, mentioned above, must now be noted in greater detail. The manner in which provision is made in a valveless tool for the supply of sutiicient fluid for an effective return stroke while yet enabling the striking of a clean sharp blow uncushioned by pre-admission, and still takingl advantage of a relatively great degree of eXpan sion of the fluid which acts on the pressure surfaces of the piston in causing' a forward stroke, is a feature of great importance. Considering the tool as with the parts in the position shown in Fig. 1, it will be seen that as the piston moves forward, the inlet port 14: will be closed after the piston has moved through about forty per cent of its stroke. From this instant to slightly after eighty per cent stroke, there will be eXpansion in chambers 7 and 8. There is thus a con-siderable reduction of pressure in cham ber 8 of the cylinder, the pressure dropping, in doubling the volume due to expansion, to perhaps less than forty per cent of the initial pressure. It will thus be evident `hat the cushioning` pressure on the opposite end of the piston must be kept at a minimum in order to avoid serious checking of the blow. After the head 9 of the piston closes the port 21, there will be a gradual building up of cushioning pressure by the compression of the trapped air in the forward end of the cylinder, but this pressure does not reach a height sufficient to seriously impede efficient striking, the pressure acting to cause the stroke exceeding, by a safe margin, the maximum cushioning pressure so caused. Now as the'pressure in chamber 8 is very much below initial pressure, itwill be obvious that on the opening of the rear end of the port 11i by the end of section 10 of the piston, chamber 8 acts as an expansion chamber located between the port 14 and the chamber 7. Owing to the expansion of the air from port 11i into this chamber, the cuf-fhioning` action of the air passing` through port 20will be much delayed in the forward end of the cylinder, and the building up of pressure sufficient to cause material checking of the piston will not occur until after impact has taken place.. @n the return stroke, the ports 14 and 20 are closed simultaneously and the expansion of the air in the forward end of the cylinder is not reduced by an exu cessive clearance volume since the chamber S is out of communication with the port 2O during expansion.4 1t is thus possible to locate the rear end of port 2() in such position as to provide an ample supply of fluid to accomplish an effective return stroke without unduly impeding the forward or striking` movement of the piston.

The pressure area 16 is preferably greater than the pressure area 18 and the return pressure area 19 is preferably equal to the combined area of the two opposed pressure areas. Thus the expansion of the pressure Huid is availed of on bot-h forward and return strokes with resultant economy7 of pres sure fluid. The construction illustrated permits the use of a relatively light piston with relatively large pressure' areas and large ports, all of which contribute to the rapid, efficient and economical operation of the tool.

iVhile I have shown and described one embodiment of my invention, it will be understood that changes involving omission, substitution, alteration, rearrangement or reversal of elements, Imay be made without departing from the scope of my invention.

My invention and what I desire by Letters Patent to procure is defined in the following` claims:

1. In a motor, a cylinder, a piston reciprocable therein, an inlet port, fiuid distributing means comprising means for conducting,` fluid therefrom to thc opposite ends of said cylinder, means alternately connecting and. interrupting a connection of said conducting means to said inlet port. a chamber intermediate the inlet port and one end of said cylinder into whichthe fluid pressure supply expands inpassing to said last mentioned end but communicable therewith only during admission thereto, and exhaust means for said motor, y i

. ln a percussive motor, a cylinder, a pis` conducting means but` not with said chainber. y

3. ln a motor, a cylinder, a piston reciprocable therein, an inlet port, fluid distributing means comprising means for conducting fluid therefrom to one end of the cylinder during` a portion of one pass of the piston, means for conducting fluid to the opposite end of said cylinder from said'inlet port during a portion of the alternate pass of the piston, a chamber between said inlet port and lsaid last men-l tioned end of the cylinder into which the fluid expands in passing `to the latter, means for closing` communication between said expansion chamber and said last mentioned end of the cylinder during;` expansii.Te action `of the fluid simultaneously with the interruption of the supply of fluid thereto, and exhaust means for said motor.

4. In a fluid pressure percussive roch drill, a cylinder, apiston therein, 4and fluid distributing means comprising means for causingexpansive action of fluid pressure on the forward movement of the piston, and

means for admitting pressure to the forward end of said cylinder prior to the completion.

of the forward movement of the piston, said first mentioned means being operative to minimize cushioning in the forward end et' sai dcylinder ln a fluid pressure percussive rock drill,

a cylinder, a piston therein, and fluid distributing means comprising means for causing expansive action of fluid pressure on the sion is not decreased by y providing;`

forward movement of the piston vfwluueby a reduced pressure; is produced in the rear end of saidcylinder, means opened-prior to the completion ot the fori irf v ,piston conduoti. i; c pressureffor other end of said cylinder throughs duced pressure spaeewhereby cushioningzon the' forward .stroke is minimized, and means for closing communication between'said reduced pressurespace and the front end f1 said cylinder simultaneously with the termination of fluid supply thereto whereby the clearance volume4 of' thev latter is not increased.` l .i y

7. ln a fluid pressure percu'ssive rock drill, a cylinder, a piston thereim and fluid distributing means comprising means 'for causing expansive action of fluid pressure `on the forward moveni'ent ,of the pistonl 1v'vhereby a reduced pressure is produced in the rear end movement of the of said cylinder, means opened prior the completion of the forward increment of the piston for conducting fluid pres# sure for the other lend of said cylinder through said reduced pressure space whereby cushioning on the iiorward stroke'- is minimized, and means for closing` comL munlcationl between said reduced: pressure space and the frontend of said cylinder simultaneously ywith the termination of fluid supply thereto whereby the ratio of. ,expanvolume. v n

8. percussive yfluid'motor comprising, m

combination, a' cylinder having` coanialbores of different diameters,` a piston having` heads fitting said bores, said heads cooperating with said bores to form` asmall chamber, arge chamber and airintermediate cha ber, and fluid distributing means for sai motor comp 1ising` conduit means communis eating with said small chamber and adapted for connection to said intermediate chamber, an inlet communicable with said small chambemand means for placing` said vconduit in communication with said intermediate chain ber when communication between said inlet and said small chamber .is closed.

9. A. fluid motor comprising a cylinder,

excess clearance pressure chamber, and'pressure fluid supply-V I ing and distributing means associated with said cylinder-and controlled by said piston,

said means comprising a fluid inlet, a pas-` sage connecting` said opposite pressure chambers, a passage opening intoone end of the smaller chamber, and means adapted to connect said small and intermediate` pressure chambers by of said last mentioned passage, said piston beingl movable into opposite positions to place either of said passages in communication with said inlet while closing the other ofsaid passagesl said piston, seid me?,1 s coinprisri 10i A inid motor comprising s cylinder, e piston therein,` seid cylinder end piston providing opposite rel etively large and smell pressure chambers and en intermediete gressure chamber, andv pressure fluid supplying end distrib-ting ineens associated with said cylinder end controlled by seid piston, seid meens comprisingl si fluid inlet, a passage connecting said opposite pressurechambers, e passage opening into the smaller chamber, an@ m adapted to connect seid smell and intermediate pressure chambers by Way of Atid lest mentioned passage, seid piston being movable into opposite positions to place one end of either of seid passages in communication with said inlet While co'xf'erine' one end ot the other of seid psfmnges. 'Y

il. .fr fluid motor co i s, cylinder having opposite portions relatively sind smell rcross sectional eren, s piston 'hs-rrelatively lorv'e and smell heads fitting si cylinder portions re iectively end en intermediate reduced g'mortionn and pressure .tl u. idY sri p plyin and distributing means essoeieted with seid cylinder and controlled by rglnld inlet comnninicsting` with said sLA .ill cylinder portion, s passage connecting thev opposite ends of said s all ycj-,rlinder portion, `end :i passage connectingt large end smell cylinder portions, seid piston Twhen in opposite positions alternatively placing one or the other of seid passs'es in communiee tion with seid inlet'while closing the rein einj ing passage.

i2. A fluid motor comprisingf @cylinder haring' opposite portions ot' relatively large end smell cross sectional eres, piston hering;` relatively large andy smell heads fittingsaid cylinder portions respectively and an intermediate reduced portion, and pressure Huid supplying and distribnting` means essoy i inserer cisted With said cylinder end controlled rby seid piston, said means comprising;l s Huid inlet con'imnnicsting with seid smell cylinder portion, ev passage connecting` the opposite ends oil.: said smell cylinder portion, and e passage connecting seid large end smell cylinder portions, the smell heed oit said pisH ton when in one position covering one end of one ot seid passages While placing1 the aidjacent end of the other of passages vin communication with seid inlet, and in an# other position coveringA the end of seid lest named passage While placing' the end ot seid named pessege in Icomiinmic'ation with sein inlet.

1" A. percm` in combination, e cylinder l Wins-g coaxial bores oi diil'erent diam rs, :i piston having.; portions fitting seid bores, seid portions ccoperatingv With seid bores to form :i pair oii chambers of di'lferent diameters in which fluid may ect to effect s :torward strolre and s single chamber in which fluid may act to elect n. return stroke, and fluid distributing` means for said motorr comprisingi con-` duit meer controlled by seid. piston through iiiich said peirof chambers are intermittently connected, en inlet communicable with seid smaller cylinder bore, end s groove in seid piston operative to bring said inlet into coinnmnicstion with seid peir of chambers, seid parts being constructed and arranged to perl it communication betr-.reen seid pair of chambers at e time when neither communicates with ssidinlet.

in testimony whereof, l have signed my neme' to this specification, in the iresence oli two subscribing Witnesses.

ELMER GRTIN.

Witiiesses rlnononn B. JoHANNs, Bonner Cross.

fe .luid'motor comprising.` 

